This project, in collaboration with Drs. John Carpten and Jeffrey Trent of NHGRI and with Drs. Maurine Hobbs, Raj Thakker, Bin Teh, Catharina Larrson, R. Marks and Silvano Presciuttini, aims to narrow the region on chromosome 1 where a locus for hyperparathyroidism with jaw tumors (HPT-JT)has been mapped by several previous linkage studies, and to eventually clone and characterize this gene. This year, analyses have been performed on new genetic markers for pedigrees from several sites and the critical region (most probable location of the gene) has been further refined. A newly developed haplotype method for detecting association has been applied to these data, giving further evidence to narrow the critical region. Molecular genetic studies have been performed by our collaborators to identify this gene. The location of the gene that we currently believe to be the disease susceptibility locus is in the region predicted by our analyses to be the most likely location. A manuscript is currently in preparation that will present the linkage, haplotype and cloning results. In the future, we plan to use these data to examine questions about our haplotype sharing method and its uses in localizing disease genes.